Many RF and microwave systems rely on accurate phase control to insure proper circuit performance. Many devices used in these systems do not have temperature invariant phase characteristics. The phase temperature variation can be large enough to degrade the system to the point where compensation is required. One type of phase shifter is an allpass filter network formed of a plurality of capacitors and inductors connected in series and parallel relation. The amplitude of a signal which passes through such a filter remains unchanged regardless of the signal frequency. However, the phase will change with frequency depending upon the center frequency (or resonant frequency) of the filter. FIG. 1 is a graph showing a typical amplitude and phase response through an allpass filter. The dash line shows that the amplitude remains substantially constant over a range of frequencies whereas the solid line shows that the phase changes with frequency. The phase change with frequency is most linear around the 180.degree. phase shift point. The 180.degree. point is the most useful operation point for the filter, although other points may be used in order to achieve a particular slope or to match the characteristics of the system or device that is to be compensated. However, the variation in phase will change with changes in temperature.